Lots of bad speculation
The NTSB preliminary would seem to indicate an approach turn stall. The stall warning horn was sounding for 20 seconds prior to impact.
I don't know what training this pilot had in this aircraft but it would seem that an approach turn stall should have been in the syllabus. "Should" being a very big word.
I studied this event closely because I'm also a small business owner who flies light jets single pilot. While I think there is nothing inherently dangerous about Part 91 single pilot jet ops, I recognize that there is more that can go wrong and more skill is required. Consequently the training requirements, even for someone with lots of experience, are much higher than even for turboprops.
When I saw that it was a likely approach turn stall I thought "I don't think that's a mistake I would make". What I didn't want to hear is that the pilot did everything right and still crashed. I don't fly a Phenom and don't know anything about its stall characteristics but the aircraft I fly (mainly Citations) are pretty hard to stall if you are even remotely clueful.
As for operating light jets from short runways I do it all the time - but you have to be even more careful. If your approach isn't stabilized, go around. There's too many things that can bite you - excessive sink rate being one of the most obvious.
But to say "everyone who flies light jets should have 2 pilots" (which I've seen all over the internet) defeats the whole purpose of having a light jet in the first place. I need to fly by myself for business - I'd switch to a TBM or King Air if I couldn't fly jets single pilot. But the jets provide quite a bit of increased business flexibility and efficiency due to their speed.